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The document proposes a new concept called the New Worlds Imager (NWI) as an alternative to the Terrestrial Planet Finder (TPF) for directly imaging exoplanets. The NWI would use a large starshade and interferometer in space to block starlight and combine light from exoplanets to image them with resolutions of 100km at 10 parsecs. It could directly image biomarkers on Earth-like exoplanets within the next 10-20 years using existing technology and would further the goal of finding life outside our solar system.
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- 1. New Worlds ImagerWebster CashUniversity of Colorado
- 2. New Worlds Imager An Alternative to TPF Webster CashUniversity of ColoradoJim GreenEric SchindhelmNishanthRajanJeremy KasdinPrinceton UniversityBob VanderbeiDavid SpergelEd TurnerSara SeagerCarnegie Institution –WashingtonAlan SternSouthwest Research Institute –BoulderSteve KilstonBall AerospaceErik WilkinsonMike LeiberJim LeitchJon ArenbergNorthrop GrummanRon PolidanChuck LillieWillard SimmonsMITand growing…
- 3. Exo-Planets •Exo-planets are the planets that circle stars other than our Sun. •There are probably 10,000 exo-planets within 10pc (30 light years) of the Earth.
- 4. Are Any Habitable?? Are Any Occupied??? To Be Human Is to Want to Know
- 5. Some Poetry (?) Certain knowledge of a destination could drive future generations to cross the awful gulf of interstellar space.
- 6. The Problem with Exo-Planet Studies •Planets are lost in the glare of parent star. •The Earth as viewed from light years is 10 billion times fainter than the Sun.
- 7. Terrestrial Planet Finder•Telescopes must be PERFECT to suppress scatter: λ/5000 surface, 99.999% reflection uniformity•TPF is verydifficult•Is there any easier way?
- 9. A Pinhole Camera Meets The Requirements: Perfect Transmission No Phase Errors Scatter only from edges –can be very low Diffraction Issues Remain Large Distance Set by 0.01 arcsecrequirement diffraction: λ/D = .01” ÆD = 10m @500nm geometric: F = D/tan(.01”) = 180,000km
- 10. Focal Plane
- 11. View Back Toward StarshadeBackground Stars & Zodiacal LightStarshadeDiffracted Starlightaround edge fallsoutside slitSpectrographEntrance Slit(Projected) Planet LightBackground Light
- 13. View Dark Side of Starshade Target Sun
- 14. “Standard” Observatory Views Starshade ~1” resolution or somewhat better (not necessarily diffraction limited) High efficiency, low noise spectrograph (e.g. COS)
- 15. Reduces Noise Almost to Zero Detector Noise (counts) Diameter (m) Required integration time (days) to get 100,000 counts MCPglass MCPSi CCD 1 28 363 15 604800 5 1.1 15 0.6 24192 10 .3 4 0.1 6070 15 .1 2 0.06 2700 20 .07 1 0.04 1512 Assumptions: Fλ~3e-9 photons/cm2/sec/Åfor Earth at 10pc, system efficiency ~0.35, λ=5000Å. Background calculations done using MCPglass=0.5 counts/cm2/sec, MCPsilicon=0.02 counts/cm2/sec, CCD=1e-read noise and readout every 20 minutes, and a 0.03x1 mm resolution element with 0.010 mm pixels.
- 16. Orbital Considerations Need Study
- 17. Planet Finding Mode Solar System at 10pcMarsVenusEarthJupiterEarthVenus Survey to 7AU Survey Habitable Zone
- 18. Inverse Pinhole Occulter Pinspeck •Smaller Starshade –Create null zone, image around occulter •10m shade, 1m diffraction limited telescope and 20,000km separation would work •Observe entire planetary system at once •Highly affordable. Could build today
- 19. Predecessors BOSS http://umbras.org/ Starkmanshowed that starlight could be reduced by 10,000x.
- 20. Pinspeckwith 1m Telescope50,000 seconds400,000 secondsJupiterEarthVenusMars
- 21. Pinspeckwith 8m Telescope 50,000 secondsEarthMarsHalley’s Comet
- 22. Simulated Data Earth at 10pc
- 23. Spectroscopic Biomarkers WaterNecessary for habitability OxygenFree oxygen results only from active plant life OzoneResults from free oxygen Nitrous OxideAnother gas produced by living organisms MethaneLife indicator if oxygen also present VegetationRed edge of vegetation at 750nm
- 24. Photometry Photometric Imaging is Possible!
- 25. Pale Blue Planet Mission
- 26. PBP Requirements 100km Resolution at 10pc is 0.06 micro-arcseconds Interferometer requires a 1500km baseline And the same collecting area as Keck Telescope in Hawaii (10 meter diameter) We can do this right now if we have the will.
- 27. The “Freeway Mission” From the movie Contact. Dr Arrowaygets a brief glimpse of this alien landscape.
- 28. Freeway Requirements 300m resolution at 10 parsecs = 0.02 nano-arcseconds 500,000km baseline Huge collecting area –one square kilometer Right now this is impossibly expensive, but not necessarily tomorrow
- 29. The New Worlds ImagerA simulated exo-planet at 500 km resolution. Earth at 200km resolution. Oceans, continents and clouds are visible.
- 30. NWI Conceptcollector craft1500kmstarshadescollector craftcombiner 180,000km 1500km
- 31. Holding the Arrayplanet collimatorfield star collimatorprimary collectorto combinerplanet beamsfield star beamsDelay Lines –Mixers -Detectorsplanet Detectors
- 32. Fits Into NASA Planning•Identify Earth-like Planets•Search for oceans•Search for unambiguous tracers of life•Study new eco-systemsLife FinderObjective•Reacquire Earth- like planets•Perform spectroscopy with λ/δλ> 1000•Search forH20, O2, N2O, O3, etc•Survey dozens of nearby systemsScienceGoalInstrumentRequirements•Suppress starlight to below 10-10•Separate planets at .01” •Operate in visible or near IR•10m class aperture for signal•High Efficiency Spectrograph•Low noise detectors•Two craft•Shaped aperture in large, deployable light stop•10m, 1”class telescope with Rowland spectrograph•Formation flying to ~1m line of sight at 180,000km•L2 or drift away orbitMissionRequirements•HST•JWST•TPF•LISA•SIMRelevantPredecessorsNew WorldsObserverNew WorldsImagerPictures of Earth- like Planets with 100km Resolution•WorldsObserverImagerPictures Resolution
- 33. New Worlds Observer Roadmap •PinspecksvsPinholes •Minimize Size (and hence cost) •Deployment of Starshade •Orbit Tradeoff •Formation Flying •Telescope Design •Simulations and Limitations
- 34. New Worlds Imager Roadmap •Formation Flying Requirements •Interferometer Design •Image Formation •Pathlength Nulling •Simulations N.B. NWI is very challenging, but it’s the first true planet imaging architecture for which we can write specifications that are not ridiculously difficult.
- 35. Size Minimization •Pinspeckif at all possible •Diffraction dominates signal but drops with size of starshade. •I have five mathematicians working on the problem. (N.B. Mathematicians are not used to working on deadlines!)
- 36. Orbital Analysis At L4, L5 or any Sun-centered orbit, it takes .001N continuous thrust to keep a 1000kg craft in alignment. Milli-Newton thrusters are now available, and a few square meters of solar panels can power it. These thrusters can move the starshadeto the next target in a day or two. 50 planetary systems per year.
- 37. Formation Flying 1W laser can be seen at 200,000km. Can track relative to back ground stars. Craft need to be designed to find each other and align against sky. Background Stars & Zodiacal LightStarshadeDiffracted Starlightaround edge fallsoutside slitSpectrographEntrance Slit(Projected) Planet LightBackground Light
- 38. NIAC: They Bring Good Things To Life •Press Interest –Publicity Crucial to Shifting Opinions •Industry Interest –Northrop Grumman Putting in Resources •Government Interest –White Paper Put Us in NASA Roadmap –Goddard Studying This as Alternative •TPF Off-ramp?
- 39. Conclusion •Needs ThoroughStudy •If No Major Problems Emerge, then… •We have an exo-planet observatory concept that can be implemented with today’s technology •Biggest Problem may be political By 2011 By 2018